Gluten-free communion has been disapproved by the Vatican as the Catholic Church deemed ingredients other than wheat to be invalid according to strict guidelines for the Sacrament of the Holy Eucharist.

Citing a letter to bishops from the Congregation for Divine Worship and the Discipline of the Sacraments released in June, the outlet revealed that the bread used for the sacrament of the Holy Eucharist should only be made of wheat and nothing else. It should also be unleavened and prepared recently to prevent decomposition.

On top of that, Cardinal Robert Sarah, the congregation’s prefect, emphasized that bread not made purely of wheat, including gluten-free communion wafers, are considered invalid for the Eucharistic Sacrament.

“It follows therefore that bread made from another substance, even if it is grain, or if it is mixed with another substance different from wheat to such an extent that it would not commonly be considered wheat bread, does not constitute valid matter for confecting the Sacrifice and the Eucharistic Sacrament,” the Instruction Redemptionis Sacramentum issued on March 25, 2004, states as cited by Vatican Radio.

The document also deemed it “a grave abuse” for people to add ingredients such as fruit, honey, and sugar to the Eucharistic bread.

According to the cardinal who speaks on behalf of Pope Francis, while gluten-free communion wafers are not allowed, those with low gluten content can still be used “provided they contain a sufficient amount of gluten to obtain the confection of bread without the addition of foreign materials and without the use of procedures that would alter the nature of bread.”

Based on a report from USA Today, Vatican’s take on the matter comes just as more people turn to gluten-free diet.

Some people suffer from gluten intolerance and celiac disease, which are characterized by digestive issues such as bloating, gas, diarrhea, and constipation. Others also get keratosis pilaris or “chicken skin” that usually appears at the back of the arm and is caused by fatty acid deficiency and vitamin A deficiency due to fat malabsorption from a gluten-damaged gut.

Fatigue or “brain fog” is also considered a common symptom of gluten intolerance, per an article from the health website Mind Body Green.

Despite this, the Catholic Church deems gluten-free communion wafers to be invalid in order to preserve the sanctity of the Eucharistic Sacrament.

“Until recently it was certain religious communities who took care of baking the bread and making the wine for the celebration of the Eucharist. Today, however, these materials are also sold in supermarkets and other stores and even over the internet,” Cardinal Sarah states.

“In order to remove any doubt about the validity of the matter for the Eucharist, this Dicastery suggests that Ordinaries should give guidance in this regard by, for example, guaranteeing the Eucharistic matter through special certification.”

Furthermore, the publication of the circular letter aims to remind bishops and members of the clergy about the use of mustum, or unaltered grape juice that is either fresh or preserved by methods that suspend its fermentation, in the celebration of the Holy Eucharist on top of the declaration of the invalidity of gluten-free communion wafers.